A medical body area network (MBAN) system has been devised to provide a flexible platform for wireless networking of a plurality of sensors used to monitor biological data of a patient in a health care facility such as a hospital.
The MBAN system is operated at bands of 2360 MHz to 2400 MHz on the basis of the IEEE 802.15.4, and its maximum emission bandwidth is limited to 5 MHz.
If the MBAN system is operated at 2360 MHz to 2390 MHz, its transmission power has the smaller value of 1 mW and 10*log(B)dBm. At this time, B is the emission bandwidth of 20 dB. If the MBAN system is operated at 2390 MHz to 2400 MHz, its transmission power has the smaller value of 20 mW and 10*log(B)dBm, wherein B is the emission bandwidth of 20 dB.
2360 MHz to 2400 MHz is the frequency bandwidth already allocated for another wireless communication system. The MBAN system is operated on the basis of the cognitive radio technology. The cognitive radio technology means that a network or wireless communication device actively senses and determines its neighboring communication environment to adaptively change transmission and reception properties, such as frequency bandwidth, transmission power and coding scheme, which are intended for optimized communication. In this case, if the cognitive radio device senses use of another licensed user (or primary user) at a desired frequency bandwidth, the cognitive radio device is preferentially operated so as not to disturb communication of the corresponding users.
To this end, the MBAN devices are basically operated inside a registered health care facility if they are operated at 2360 MHz to 2390 MHz. In other words, the MBAN devices should control use for 2360 MHz to 2390 MHz through cooperation with another licensed user, and if another licensed user uses the corresponding bandwidth, the MBAN devices should reset all the operations at this bandwidth and resume the operation by newly using the bandwidth of 2390 MHz to 2400 MHz.
If the MBAN devices move outdoor, they should stop their operations or change a transmission bandwidth to the bandwidth of 2390 MHz to 2400 MHz used as the basic bandwidth. If the MBAN devices are operated at the bandwidth of 2390 MHz to 2400 MHz, they may be used indoor and outdoor without limitation.
However, a detailed channel arrangement and a method for searching for a channel at each frequency bandwidth have not been defined for the MBAN system.